Linear pallet stop

Abstract

A linear pallet stop smoothly decelerates a heavy pallet propelled by a conveyance system in a downstream direction and stops the pallet at a predetermined location. The linear pallet stop comprises a catch arm that is translatable and rotatable between three positions. At the first position, the catch arm first end is in the pallets path to be contacted by the pallet and translated in the downstream direction by the pallet momentum. The downstream translation is resisted by a fluid circuit acting through a cylinder and a slide that is in support contact with the catch arm. A stop surface on the catch arm strikes a fixed surface on the conveyance system at a second position of the catch arm. By retracting the slide with the fluid cylinder when the catch arm is in its second position, the catch arm rotates to a third position whereat its first end is out of the pallets path. The catch arm is guided for translation and location by cam followers that are captured within slots in housings. After the pallet has been propelled further downstream, the cylinder is operated to extend the slide and push the catch arm in the upstream direction and return it to its first position.

We claim: 
     
       1. In combination with a conveyance system that propels a pallet in a downstream direction along a path, an apparatus for decelerating and stopping the pallet comprising: a catch arm having first and second ends;   a cam follower connected to the catch arm to enable the catch arm second end to translate in upstream and downstream directions and to enable the catch arm to rotate about its second end;   a slide bearing adapted to slidably engage the catch arm intermediate the first and second ends to support the catch arm between the first and second ends thereof;   a strike surface located at a predetermined location relative to the conveyance system for being struck by the catch arm second end; and   an actuator connected to the slide bearing, the actuator forcing the slide bearing to an engagement position that pivots the catch arm into the path of the pallet, the actuator biasing the slide bearing and catch arm against downstream movement of the pallet, with the slide bearing providing resistance to rotation of the catch arm.   
     
     
       2. The combination as recited in claim 1, wherein: the catch arm is fabricated with a hook on the first end thereof that lies in the path of the pallet when the slide bearing is in the engagement position;   the catch arm second end is fabricated with a stop surface thereon; and   the catch arm stop surface is disposed to strike the strike surface after the pallet has contacted the catch arm hook and has translated the catch arm in the downstream direction against the resistance provided by the actuator.   
     
     
       3. The combination as recited in claim 1, wherein the cam follower comprises a pair of cam followers assembled to the catch arm proximate the second end thereof. 
     
     
       4. The combination as recited in claim 3, further comprising a housing to guide the cam followers as they translate in upstream and downstream directions. 
     
     
       5. The combination as recited in claim 1, wherein the slide bearing comprises: a slide member connected to the actuator; and   a slidable bearing mounted to the slide member and disposed in supporting contact with the catch arm between the first and second ends thereof, the slidable bearing cooperating with the cam follower to translate and rotate the catch arm first end into the path of the pallet when the actuator operates the slide bearing to an extended position and to rotate the catch arm first end out of the path of the pallet when the actuator operates the slide bearing to a retracted position.   
     
     
       6. The combination as recited in claim 1, wherein the actuator comprises: a single fluid cylinder connected to the slide bearing; and   a fluid circuit connected to the fluid cylinder to move the slide bearing to an extended position, and to control the fluid cylinder to decelerate the pallet after the pallet has contacted the catch arm and translated it in the downstream direction.   
     
     
       7. The combination as recited in claim 4 wherein: the housing includes a pair of housings, each housing defining a slot that guides an associated cam follower, each slot having upstream and downstream ends; and   wherein the slide bearing includes:   a slide member connected to the actuator; and   a slidable bearing mounted to the slide member, the slidable bearing being in supporting contact with the catch arm between the first and second ends thereof, the slidable bearing being slidable along the catch arm to selectively move the catch arm into the path of the pallet.   
     
     
       8. A method of decelerating and stopping an object moving along a conveyor path in a downstream direction, the method comprising the steps of: pivoting a catch arm, having first and second ends, into a first position where the first end thereof is in the path of the object;   contacting the object with the catch arm first end;   translating the catch arm in the downstream direction and simultaneously decelerating the downstream translation of the object and the catch arm without substantially pivoting the catch arm by applying a controlled force in the upstream direction by an actuator;   stopping the downstream translation of the object and the catch arm at a predetermined location along the path, wherein the catch arm is at a second position; and   pivoting the catch arm to a third position out of the path of the object by applying a controlled force in the downstream direction by the same actuator.   
     
     
       9. The method as recited in claim 8, wherein the the catch arm pivots about a cam follower located proximate the second end thereof. 
     
     
       10. The method as recited in claim 9, wherein the step of pivoting the catch arm into the first position comprises the steps of: pushing the catch arm in an upstream direction and simultaneously translating the cam follower in the upstream direction;   stopping the upstream translation of the cam follower at a predetermined location; and   rotating the catch arm about the cam follower and placing the catch arm first end in the path of the object.   
     
     
       11. The method as recited in claim 10, wherein the step of pushing the catch arm comprises the steps of: operating a fluid cylinder having a rod connected to a slide to push the catch arm in the upstream direction with the slide.   
     
     
       12. The method as recited in claim 11, wherein the step of translating the catch arm in the downstream direction and simultaneously decelerating the downstream translation of the object and the catch arm comprises the steps of: coupling the downstream force of the catch arm to the slide and to the fluid cylinder rod; and   controlling the flow of fluid within the fluid cylinder to resist the downstream force of the slide by the catch arm.   
     
     
       13. The method as recited in claim 12, wherein the step of controlling the flow of the fluid within the fluid cylinder comprises the step of metering the flow of fluid from the fluid cylinder to gently stop the downstream translation of the object and catch arm at the predetermined location without bounceback. 
     
     
       14. An apparatus for decelerating an object moving along a path in a downstream direction, the apparatus comprising: a base;   a catch arm coupled to the base, the catch arm being adapted to engage the object when the catch arm is in a first orientation and to disengage from the object when the catch arm is in a second orientation; and   a single controllable actuator means for: (a) applying a decelerating force to the catch arm against the downstream movement of the object when the catch arm is in the first orientation and   (b) controlling the movement of the catch arm between the first and second orientations.     
     
     
       15. The apparatus as recited in claim 14, wherein the base includes a housing, wherein the catch arm is connected to the housing at a pivot point such that the catch arm rotates about the pivot point between the first and second orientations. 
     
     
       16. The apparatus as recited in claim 15, wherein the housing includes a slot disposed substantially parallel to the path, and wherein the pivot point of the catch arm moves linearly within the slot when the catch arm is in the first orientation while the object is decelerating. 
     
     
       17. The apparatus as recited in claim 16, wherein the actuator means includes a single fluid cylinder coupled to a fluid circuit, wherein the fluid circuit controls the amount of decelerating force which the catch arm applies against the object. 
     
     
       18. The apparatus as recited in claim 15, wherein the actuator means includes a cam follower adapted to at least partially support the catch arm when the catch arm rotates about the pivot point between the first and second orientations. 
     
     
       19. The apparatus as recited in claim 18, wherein the actuator means includes a single fluid cylinder coupled to a fluid circuit, wherein the fluid circuit controls the movement of the cam follower to move the catch arm between the first and second orientations. 
     
     
       20. The apparatus as recited in claim 14, wherein the object is a pallet moving along a conveyor system.